1. Field of the Invention
The present invention relates to a valve device and a poppet.
2. Description of Related Art
Conventionally, a gas tank installed in a fuel cell vehicle etc. is provided with a valve device that controls the supply and exhaust of high-pressure hydrogen gas stored inside the tank. Such a valve device includes a body with a gas flow channel formed therein that provides communication between the inside and the outside of the gas tank, and a valve mechanism that controls the flow of hydrogen gas through the gas flow channel. A pipe extending from an external apparatus (e.g., hydrogen gas supply source) is coupled to the gas flow channel through a joint mounted on the body (e.g., Japanese Patent Application Publication No. 2013-29161).
Specifically, as shown in FIG. 9, a body 121 of the valve device described in JP 2013-29161 A has a mounting hole 123 on which a joint 122 is mounted. The body 121 further has a filling channel 124 that communicates with the mounting hole 123 at the bottom surface of the mounting hole 123 and serves as a gas flow channel through which the gas tank is filled with hydrogen gas. As a pipe (not shown) is coupled to the joint 122, the pipe is connected to the filling channel 124.
The filling channel 124 is provided with a check valve 132 that prevents hydrogen gas from being released through the mounting hole 123 to the outside. At the end on the side of the mounting hole 123, the filling channel 124 has an enlarged part 133 communicating with the mounting hole 123 and a valve housing part 134 adjacent to the enlarged part 133. The inner diameter of the valve housing part 134 is smaller than that of the enlarged part 133 and larger than that of the other part of the filling channel 124. The check valve 132 includes a valve seat 136 with a valve port 135 formed at the center, a poppet 137 that can open and close the valve port 135 (filling channel 124) by coming into and out of contact with the valve seat 136, and an urging member 138 that urges the poppet 137 toward the valve seat 136.
When the tank is not being filled with hydrogen gas, the poppet 137 remains in close contact with the valve seat 136 under the pressure of hydrogen gas stored inside the tank and the spring load of the urging member 138 to thereby keep the valve port 135 closed and prevent the hydrogen gas from being released through the filling channel 124.
To fill the tank with hydrogen gas, the check valve is opened by pushing the poppet 137 downward under the load of the hydrogen gas. Since this filling process utilizes the differential pressure between the filling pressure and the tank internal pressure, the gas flow rate decreases as the differential pressure decreases.
As hydrogen gas tanks in recent years are designed for increasingly higher pressure (e.g., 70 MPa) to increase the hydrogen storage capacity, higher reliability is required of check valves. As shown in FIG. 10, the check valve includes a closure part 141 that comes into and out of contact with the valve seat 136 at the leading end, and the part of the check valve except the leading end includes a portion 140 and is formed in a cylindrical shape with an inner cavity 143. The check valve further has a plurality of hydrogen passage holes 142 (i.e., side holes) at a right angle to the inner cavity 143 (i.e., the shaft center of the check valve).
When the inside of the hydrogen gas tank is brought to high pressure, this type of valve body experiences a noise phenomenon as hydrogen gas passes through the hydrogen passage holes 142. One solution to reduce the noise is to form side holes 144 that are oblique to the shaft center of the check valve as shown in FIG. 11 and FIG. 12, instead of forming the hydrogen passage holes 142 at a right angle to the shaft center of the check valve. In this case, however, a problem with the durability of the check valve may arise in return for being able to suppress the noise. Specifically, a phenomenon has been found that the seat surface of the valve seat wears abnormally as the valve body rotates around the shaft center thereof (on its own axis) during the valve closing action.
Although the above is the example where the side holes 144 are oblique to the inner cavity 143, a similar problem with the durability of the valve device arises when the valve body itself rotates around the shaft center thereof (on its own axis), even if the side holes are not oblique to the inner cavity, i.e., even if the side holes are formed at a right angle to the shaft center of the valve body.